During the operation of a machine tool the tools used are subject to wear. The geometry of the tool changes, depending on the type of load and the machining method, such as for example turning, milling or boring. This change impacts on the workpiece to be manufactured using the machine tool. Up to a certain level this change in the geometry of the tool can be compensated for by the machine tool controller with the aid of compensating algorithms. In this process the current tool geometry is detected and the machining process is changed as a function of the measured wear offset.
One example of this is a milling head shortened by wear. In such an instance the machine tool controller modifies the tool correction data, so that the center of the tool is positioned precisely at the point required in each instance during machining.
However the machine tool controller is only able to compensate for such tool wear to a limited extent. It is thus not possible to modify the general pattern of the milling paths, which is predetermined by the program of the numerical controller present in each instance. This means that despite a tool correction carried out by means of the machine tool controller the workpiece to be manufactured deviates from its setpoint geometry due to a change in the cutter diameter or the contour of the milling head due to wear.
To maintain the quality of the workpieces to be manufactured and at the same time to keep the costs of new tools as low as possible, it is desirable to identify the most favorable time for replacing the tool.
It is already known for this purpose that fixed wear variables can be specified. These values are generally based on values from the user's experience.
The machining process can also be simulated with a modified tool geometry. A number of NC validation tools are known for this purpose, which also permit an inputting of modified tool geometries, for example Vericut, Unigraphics-NX and Tecnomatix. This inputting and the updating of the various simulation parameters and the models to be simulated are effected manually and therefore require a high level of outlay.